Magnetic head device and magnetic disk drive for reading information from or writing information to a medium

ABSTRACT

A magnetic head device for reading information from or writing information to a rotating magnetic recording medium includes a magnetic pole for reading the information from or writing the information to the medium and a slider for supporting the magnetic pole, and moving the magnetic pole on the medium. The slider includes a contact portion for supporting the magnetic pole, and keeping the magnetic pole in contact with the medium, a flying portion positioned above the medium, the flying portion having a first surface where dynamic pressure generated by fluid-flow caused by rotation of the medium, and a connecting member portion having a mass less than that of the flying member, portion, the connection portion connecting between the contact portion and the flying portion.

This is a continuation of application Ser. No. 08/359,699, filed Dec.20, 1994, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a magnetic head device and a magneticdisk drive which is capable of reading information from writinginformation to a magnetic recording medium, as the magnetic head deviceis kept in contact with the magnetic recording medium.

2. Description of the Related Art

Efforts continue to increase the recording density of a magnetic diskdrive using a hard disk. Due to the increase of recording density, thespacing between a magnetic head device (called “head” hereinafter) and amagnetic recording disk (called “disk” hereinafter) serving as amagnetic recording medium, is decreasing. Ultimately, it will benecessary to read/write information on the disk as the head is kept incontact with the disk.

The most important problem for carrying out the contact reading/writingis to reduce wear of the head and the disk. In order to reduce the wear,it is necessary to keep the contact force applied between the head andthe disk at a low level and stable.

A brief structure of a prior art head having a taper-flat type sliderwill be described with reference to FIG. 13.

A taper-flat type slider 100 has a slider surface 102 which is opposedto a disk 101. The slider surface 102 includes a tapered surface 102 abeing slanted in a direction close to the disk along the rotatingdirection of the disk(shown by the arrow in FIG. 13), and a flat surface102 b being substantially parallel to the disk, when the disk stopsrotating. Dynamic pressure (gage pressure) Ph generated by fluid-flowcaused by rotation of the disk is applied to the slider surface 102.According to the flying slider method used in a prior art hard diskdrive, the slider 100 flies above the disk 101 at a predetermineddistance by means of the dynamic pressure Ph. In this case, however, thetrailing edge serving as a contact portion 103 of the slider 102 is keptin contact with the surface of the disk 101. A magnetic pole(not shown)is mounted on the contact portion 103 to read/write information on thedisk 101, as the magnetic pole is kept in contact with the disk.

There are three forces being applied to the slider 100 when the disk 101rotates. They are a load F, a fluid force fh, and a contact force fc.The load F is applied at a pivot position 104 by a suspension (notshown). The fluid force is a sum of the dynamic pressure Ph. It isapplied at the position 105 at the center of the distribution of thedynamic pressure Ph. The contact force is applied at the contact portion103 from the disk 101.

The relation of these forces (F, fh, fc) is shown in the followingequation (1). $\begin{matrix}{{fc} = {\frac{{1h} - {1p}}{1h}F}} & (1)\end{matrix}$

“lp” is the lateral distance between the pivot position 104 and thecontact portion 103, and “lh” is the lateral distance between theposition 105 where the fluid force is applied and the contact portion103.

According to equation (1), it is necessary that the distance lh becomeslong and a distance between the position 105 and the pivot position 104is short, in order to keep the contact force fc at a low level. However,in the prior art taper-flat type slider, it is difficult to set thedistance lh to be long, because the position 105 is located along therotating direction of the disk 101 from the center of the total lengthof the slider 100.

The variation of the contact force fc according to the positioning errorbetween the slider surface 102 and the contact portion 103 will bedescribed.

As shown in FIG. 14, the slider 100 has three degrees of freedom. Theyare pitching(108), rolling(107), and translational(106) degrees offreedom. Stiffness of the fluid film between the slider surface 102 andthe surface of the disk 101 keeps the condition of the slider 100 stablewith regard to the three degrees of freedom. For example, the pitchingstiffness will be described with reference to FIGS. 15(a)-15(c). FIG.15(b) shows the standard condition of the slider. If the angle α′ formedbetween the slider surface 102 and the surface of the disk 101 (pitchangle) becomes smaller than the pitch angle α in the standard condition,as shown in FIG. 15(a), moment 109 occurs to restore the pitch angle. Ifthe pitch angle α″ becomes larger than the pitch angle α in the standardcondition, as shown in FIG. 15(c), moment 110 also occurs to restore thepitch angle. According to the prior art taper-flat type slider, theslider surface 102 is formed long enough to secure the pitchingstiffness in the rotating direction of the disk.

When a positioning error between the slider surface 102 and the contactportion 103 is made, the contact force fc varies. This variation of thecontact force fc will be described with reference to FIGS. 16(a)-16(c).

FIG. 16(b) shows the standard condition. FIG. 16(a) shows the conditionthat the contact portion 103 extends further than the contact portion ofthe standard condition. In this case, as the pitch angle α′ in FIG.16(a) becomes smaller than the pitch angle α in the standard condition,the moment 109 occurs to restore the pitch angle. Therefore, the contactforce increases by dfc to balance the moment 109.

FIG. 16(c) shows the condition that the contact portion 103 is recessedrelative to the contact portion of the standard condition. In this case,as the pitch angle α″ becomes larger than the pitch angle α in thestandard condition, the moment 110 occurs to restore the pitch angle.Therefore, the contact force decreases. Finally, the contact force fcbecomes zero, and the slider 100 floats above the disk 101.

The influence of inertia which occurs due to the undulation of the disk,the vibration of the disk, or shock applied to the device from outsidewill be described with reference to FIG. 17. The inertia fg is appliedat the center of gravity of the head (G) depending on the mass of theslider 100 and equivalent mass of the suspension (not shown). Theposition of G is located on the line connecting the center of gravity ofthe slider 100 (Gh) with the pivot position (Gp) where the equivalentmass of the suspension is applied. The inertia fg is divided between thevariation of the fluid force dfh and the variation of the contact forcedfc. The variation of the contact force dfc is shown in the followingequation (2). $\begin{matrix}{{dfc} = {\frac{{1h} - {1g}}{1h}{fg}}} & (2)\end{matrix}$

“lg” is the lateral distance between the position of G and the contactportion 103.

According to equation (2), it is necessary for the distance lh betweenthe position 105 where the fluid force is applied and the contactportion 103 to be long and for the position 105 to be located near theposition of G in order to reduce the variation of the contact force dfc.But, in the prior art taper-flat type slider, it is difficult to set thedistance lh to be long, because the position 105 and the pivot position(Gp) are located along the rotating direction of the disk 101 from thecenter of the total length of the slider 100.

A phenomenon of stiction between the head and the disk will bedescribed. In a prior art magnetic disk drive having a flying typeslider, the slider lands on the disk and the slider surface is kept incontact with the surface of the disk, when the disk stops rotating. Itis called a constant·start·stop method (CSS method) as usual. Accordingto the CSS method, stiction occurs by the influence of water orlubricant existing between the slider and the disk. Stiction preventsthe disk from starting to rotate. In the prior art, the surface of thedisk is made uneven to prevent stiction. However, it is necessary forthe surface of the disk to be flat in the case of contactreading/writing, so that the the contact condition is stable. Therefore,stiction is a significant problem in the practice of contactreading/writing.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a magnetic head devicewhich can maintain a contact condition between the magnetic head deviceand a magnetic recording medium stably, which can maintain a contactforce being applied to the magnetic head device from the magneticrecording medium at a low level, and which can reduce wear of themagnetic head device and the magnetic recording medium.

Another object of the present invention is to provide a magnetic diskdrive for which life can be extended, as the wear of the magnetic headdevice and the magnetic recording medium is reduced.

In accordance with the present invention, there is provided a magnetichead device for reading information from or writing information to arotating magnetic recording medium, comprising: a magnetic pole forreading the information from or writing the information to the medium;and a slider supporting the magnetic pole, and to move the magnetic poleon the medium; the slider including: a contact portion supporting themagnetic pole, and to contact the medium, a flying member to fly abovethe medium, having a first surface for confronting the medium to receivedynamic pressure generated by fluid-flow caused by rotation of themedium, and a connecting member having a mass less than that of theflying member, coupled between the contact portion and the flyingmember.

Also in accordance with the present invention, there is provided amagnetic head device for reading information from or writing informationto a rotating magnetic recording medium, comprising: a magnetic pole forreading the information from or writing the information to the medium; aslider supporting the magnetic pole, and to move the magnetic pole onthe medium; the slider including: a contact portion supporting themagnetic pole, and to contact the medium, a flying member to fly abovethe medium, having a first surface for confronting the medium to receivedynamic pressure generated by fluid-flow caused by rotation of themedium; and means for applying a load to the slider to balance with thedynamic pressure and a contact force applied to the contact portion fromthe medium, wherein the first surface is a curved surface, a center ofcurvature of the first surface being proximate a position where the loadis applied.

Further in accordance with the present invention there is provided amagnetic disk drive, comprising: a magnetic recording disk; means forrotating the disk; and a magnetic head device for reading informationfrom or writing information to the disk; the head device including; amagnetic pole for reading the information from or writing theinformation to the disk, and a slider supporting the magnetic pole, andto move the magnetic pole on the disk; the slider including: a contactportion supporting the magnetic pole, and to contact the disk, a flyingmember to fly above the disk, having a first surface for confronting thedisk to receive dynamic pressure generated by fluid-flow caused byrotation of the disk, and a connecting member having a mass less thanthat of the flying member, coupled between the contact portion and theflying member.

Additionally in accordance with the present invention, there is provideda magnetic disk drive, comprising: a magnetic recording disk; means forrotating the disk; a magnetic head device for reading information fromor writing information to the disk; the head device including: amagnetic pole for reading the information from or writing theinformation to the disk, and a slider supporting the magnetic pole, and,to move the magnetic pole on the disk; the slider including: a contactportion supporting the magnetic pole, and to contact the disk, and aflying member to fly above the disk, having a first surface forconfronting the desk to receive dynamic pressure generated by fluid-flowcaused by rotation of the disk; and means for applying a load to theslider to balance with the dynamic pressure and a contact force appliedto the contact portion from the disk, wherein the first surface is acurved surface, a center of curvature of the first surface beingproximate a position where the load is applied to the slider.

Additional objects and advantages of the present invention will be setforth in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the present invention,or may be realized and obtained by means of the instrumentalities andcombinations particularly pointed out in the appended claims.

BREIF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate presently preferred embodiments ofthe present invention and, together with the general description givenabove and the detailed description of the preferred embodiments givenbelow, serve to explain the principles of the present invention inwhich:

FIGS. 1(a)-1(c) show top, side and end schematic views of a magnetichead device according to a first embodiment of the present invention;

FIG. 2 is a explanatory view showing a variation of the position wherethe fluid force is applied in FIG. 1;

FIGS. 3(a) and 3(b) show top and end schematic views of a magnetic headdevice according to a second embodiment of the present invention;

FIGS. 4(a) and 4(b) show top and end schematic views of a magnetic headdevice according to a third embodiment of the present invention;

FIGS. 5(a)-5(d) are schematic views of a magnetic head device accordingto a fourth embodiment of the present invention;

FIGS. 6(a)-6(c) are top, side and end schematic views of a magnetic headdevice according to a fifth embodiment of the present invention;

FIGS. 7(a)-7(c) are top, side and end schematic views of a magnetic headdevice according to a sixth embodiment of the present invention;

FIGS. 8(a)-8(c) are top, side and end schematic views of a magnetic headdevice according to a seventh embodiment of the present invention;

FIGS. 9(a)-9(c) are top, side and end schematic views of a magnetic headdevice according to an eighth embodiment of the present invention;

FIG. 10 is a schematic view showing a magnetic head device according toa ninth embodiment of the present invention;

FIGS. 11(a)-11(c) are explanatory views showing the variation of thecontact force according to the positioning error between the slidersurface and the contact portion in FIG. 10;

FIG. 12 is a schematic view showing a magnetic disk drive in which themagnetic head device of the present invention is used;

FIG. 13 is a schematic view showing a prior art taper-flat type sliderincluding a contact portion;

FIG. 14 is an explanatory view showing degrees of freedom in the priorart flying type slider;

FIGS. 15(a)-15(c) are explanatory views showing the pitching stiffnessof the prior art flying type slider;

FIGS. 16(a)-16(c) are explanatory views showing the variation of thecontact force according to the positioning error between the slidersurface and the contact portion;

FIG. 17 is an explanatory view showing the variation of the contactforce according to the influence of inertia.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will now be described withreference to accompanying drawings.

A structure of a magnetic head device according to the first embodimentof the present invention will be described with reference to FIGS.1(a)-1(c) which are top, side and end views, respectively.

A magnetic head device (called “head” hereinafter) comprises a magneticpole (not shown) and a slider 2. The slider 2 includes a flying member3, a contact portion 4, and a connecting member 5. The connecting member5 is located between the flying member 3 and the contact portion 4. Theslider 2 is formed to have a generally T-letter shape. The magnetic poleis mounted on the contact portion 4, so that it reads/writes informationto a magnetic recording disk (call “disk” hereinafter, not shown). Aload F is applied to the slider 2 at a pivot position 6 with asuspension (not shown). The load F is divided between a fluid force fh,which is a sum of dynamic pressure generated by fluid-flow caused byrotation of the disk, and a contact force fc applied to a contactsurface 4 a of the contact portion 4 from the disk. The relation ofthese forces (F, fh, fc) is shown in previously described equation (1).

The connecting member 5 has a surface 5 a which confronts the disk. Thearea of the surface 5 a is smaller than that of a surface 7 of theflying member 3 which confronts the disk (slider surface). The surface 5a is recessed from the slider surface 7. The contact surface 4 a has avery small area, so that the dynamic pressure applied to the contactsurface 4 a is small. According to this structure, the fluid force fh ismainly applied to the slider surface 7. A position 8 where the fluidforce fh is applied is located far from the contact portion 4. As aresult, it is possible to keep the contact force fc at a low level,because the distance lh between the position 8 and the contact portion 4becomes long in equation (1).

The mass of the connecting member 5 is less than that of the flyingmember 3. The center of gravity of the head (G) depends on the mass ofthe flying member 3 and equivalent mass of the suspension. In thepreviously described equation (2), a distance lg between the position ofG and the contact portion 4 becomes long. As a result, it is possible toreduce the variation of the contact force fc caused by inertia whichoccurs due to the undulation of the disk, the vibration of the disk, oran external shock applied to the device. Particularly, when the distancelg is equal to the distance lh, the inertia is balanced with the fluidforce fh only, so the contact force fc does not vary.

The maximum length L of the slider surface 7 along the rotatingdirection of the disk (shown by the arrow in FIG. 1(b)) is shorter thanthe maximum width W of the slider surface 7 along the directionsubstantially perpendicular to the rotating direction of the disk. Thisstructure is opposite to the prior art taper-flat type slider. As thelength L becomes shorter, the pitching stiffness of the fluid filmbetween the slider surface 7 and the surface of the disk becomes lower.Therefore it is possible to reduce the variation of the contact force fcaccording to the positioning error between the slider surface 7 and thecontact portion 4. As the width W becomes larger, the translationalstiffness and rolling stiffness of the fluid film between the slidersurface 7 and the surface of the disk are higher.

According to the prior art flying type slider, it is necessary toprovide a very small space between the slider and the disk, and thedimensional accuracy of the slider must be kept at a high level. If thedimensional accuracy is reduced, it is difficult to achieve sufficientread/write performance, and a collision occurs between the slider andthe disk. However, by utilizing the head of the first embodiment, theflying member 3 is far from the contact portion 4. Therefore, it ispossible to have a larger spacing than that of the flying type slider,and it is not necessary to keep the dimensional accuracy so high.

FIG. 2 shows a variation of the position where the fluid force isapplied, when the disk rotates constantly or starts to rotate.

The slider surface 7 includes a tapered surface 7 a slanted in adirection close to the disk along the rotating direction of the disk,and a flat surface 7 b substantially parallel to the disk, when the diskstops rotating. When the disk rotates at constant rate, the position 8where the fluid force fh is applied is located at the flat surface 7 b,and the pivot position 6 is located along the rotating direction of thedisk from the position 8. However, when the disk starts to rotate, theposition 8′ where the fluid force fh′ is applied is located at thetapered surface 7 a. Thus according to equation (1), the contact forcefc is larger when the disk starts to rotate. Wear of the contact portion4 or the disk may occur, when the disk starts to rotate. The best way toavoid such wear is to coincide the position 8 with the position 8′. Forexample, when an area of the tapered surface 7 a is larger than that ofthe flat surface 7 b, the position 8 moves toward the side of thetapered surface 7 b. Therefore it is desirable to make the area of thetapered surface 7 a larger than that of the flat surface 7 b. If thearea of the tapered surface 7 a becomes larger than that of the flatsurface 7 b, a contact area between the slider surface 7 and the diskbecomes small, and stiction may be reduced. This structure is useful tomake the system of contact reading or writing information to a diskwhich is very flat.

A structure of a magnetic head device according to a second embodimentof the present invention will be described with reference to FIGS. 3(a)and 3(b) which are top and end views, respectively.

The slider surface 7 of this embodiment is formed to have a concavesurface confronting the disk, the concave curvature occurring along thedirection perpendicular to the rotating direction of the disk. When thedisk stops rotating, the slider 2 is in contact with the disk at theedges 3 a, 3 b of the flying member 3. The areas of these edges 3 a,3 bare very small, so it is possible to reduce stiction.

A structure of a magnetic head device according to a third embodiment ofthe present invention will be described with reference to FIGS. 4(a) and4(b) which are top and end views, respectively.

The slider surface 7 of this embodiment is formed to have a convexsurface confronting the disk, the convex curvature occurring along thedirection perpendicular to the rotating direction of the disk. When thedisk stops rotating, the slider 2 is in contact with the disk at thecenter portion 3 c of the flying member 3. The area of the centerportion 3 c is very small, so it is possible to reduce stiction.

A structure of a magnetic head device according to a fourth embodimentof the present invention will be described with reference to FIGS.5(a)-5(d).

As seen in FIG. 5(d) which is a top view of the head device, theconnecting member 5 of this embodiment has a connecting surface 9 whichconnects between the slider surface 7 and the contact portion 4. Thesurface 9 is raised relative to the remainder of the surface of theconnecting member 5. The slider surface 7, the connecting surface 9, andthe contact portion 4 which confront the disk are formed to be convexalong the rotating direction of the disk. When the disk stops rotating,the top of the convex surface, for example the part of the slidersurface 7 and the connecting surface 9, as shown in FIG. 5(a) anddesignated by “(a)” in FIG. 5(d), is kept in contact with the disk. Thearea of the top of the convex surface is very small, so it is possibleto reduce stiction.

When the rotational speed of the disk is small, the part of theconnecting surface 9, as shown in FIG. 5(b) and designated by “(b)” inFIG. 5(d), is kept in contact with the disk because the pitch angle ofthe slider 2 is also small. When the disk rotates constantly, the pitchangle becomes large enough to keep the contact portion 4 in contact withthe disk, as shown in FIG. 5(c) and designated by “(c)” in FIG. 5(d). Ingeneral, when the the rotational speed of the disk is small, the flyingcondition of the slider 2 is unstable, so that a large contact force maybe applied to the contact surface of the slider 2. According to thisembodiment, when the rotational speed of the disk is small, the magneticpole (not shown) is not worn down because the contact portion 4 is notkept in contact with the disk.

A structure of a magnetic head device according to a fifth embodiment ofthe present invention will be described with reference to FIGS.6(a)-6(c) which are top, side and end views, respectively.

The slider surface 7 which is described in FIG. 1 is divided into twoparts 7 c, 7 d by a groove 10. The groove 10 is contiguous with theconnecting surface 5 a of the connecting member 5. In this structure,the maximum length L of the slider surface 7 along the rotatingdirection of the disk is defined to be the same as in the firstembodiment. The maximum width of the slider surface 7 along thedirection perpendicular to the rotating direction of the disk is definedtop be the sum of the maximum width W1, W2 of parts 7 c, 7 d of theslider surface 7 in such direction:

W=W 1+W 2  (3)

According to this definition, the maximum length L is shorter than themaximum width W. Since the pitching stiffness of the fluid film betweenthe slider surface 7 and the surface of the disk becomes lower, it ispossible to reduce the variation of the contact force caused by thepositioning error between the slider surface 7 and the contact portion4. Also, the translational stiffness and rolling stiffness of the fluidfilm between the slider surface 7 and the surface of the disk becomehigher.

Sliders having a variety of structures can readily be constructed bymeans of etching methods. According to the same definitions of themaximum length L and the maximum width W, they produce the same effectsas described above.

A structure of a magnetic head device according to a sixth embodiment ofthe present invention will be described with reference to FIGS.7(a)-7(c) which are top, side and end views, respectively.

The slider surface 7 is a single flat surface. According to thisstructure, it is possible to reduce the variation of the position 8 (notshown) where the fluid force is applied, because the slider can readilybe constructed to accurately have such a shape. For the same reason, thepivot position 6 (not shown) can be accurately controlled on the basisof the slider shape. Therefore, it is possible to determine the contactforce accurately according to the equation (1).

A plurality of projections 11 are formed on the slider surface 7. Whenthe disk stops rotating, the slider surface 7 is in contact with thedisk at the projections 11 only. If the area of the projections 11 issmall, it is possible to reduce stiction. The structures of theprojection 11 is not limited the structure shown in FIG. 7. It is alsopossible to apply the structures as shown in FIG. 3 and FIG. 4 to thisembodiment.

A structure of a magnetic head device according to a seventh embodimentof the present invention will be described with reference to FIGS.8(a)-8(c) which are top, side and end views, respectively.

A slider surface 7 includes at least two steps along the rotatingdirection of the disk. The distance between the step and the diskbecomes shorter along the rotating direction of the disk. The fluidforce is applied at the edge 12 between the adjacent steps. This type ofthe slider surface can be readily constructed accurately by means ofetching methods. According to this structure, it is possible to reducethe variation of the position 8 (not shown) where the fluid force isapplied, because it is easy to make the outward form of the slideraccurately. The pivot position 6 (not shown) can also be controlledaccurately on the basis of the shape of the slider. Therefore it ispossible to determine the contact force accurately according to equation(1). When the disk stops rotating, the slider surface 7 is kept incontact with the disk at the nearest step from the disk. If the area ofthe step is small, it is possible to reduce stiction.

A structure of a magnetic head device according to an eighth embodimentof the present invention will be described with reference to FIGS.9(a)-9(c) which are top, side and end views, respectively.

Inertia is caused by the undulation of the disk, the vibration of thedisk, or an external shock applied to the device. According to thisembodiment, the inertia is balanced with the fluid force only, so thecontact force does not vary.

The connecting member 5 has the same width as the flying member 3 alongthe direction perpendicular to the rotating direction of the disk. Sincethe slider 2 is formed to have a substantially rectangular shape, theoutward form can be readily constructed.

The maximum length L of the slider surface 7 along the rotatingdirection of the disk is shorter than the maximum width W of the slidersurface 7 along the direction perpendicular to the rotating direction ofthe disk. The connecting member 5 has a surface 5 a which confronts thedisk. The surface 5 a of the connecting member 5 is recessed from theslider surface 7. The contact surface 4 a also has a very small area, sothat only a small dynamic pressure is applied to the contact surface 4a, therefore, the fluid force fh is mainly applied to the slider surface7.

In general, the center of gravity of the head (G) depends on the mass ofthe slider 2 and equivalent mass of the suspension (not shown). Relativeto the above embodiments, the position of G in the structure, thus fardescribed, would be located further along the rotating direction of thedisk, according to equation (2), the greater part of the inertia isallocated to the contact force, because the distance lg (not shown)between the position of G and the contact portion 4 becomes short. Thisis a cause of the variation of the contact force. In order to move theposition of G in the direction opposite to the rotating direction of thedisk, a projection 13 for counter-weight is located at the opposite sideof the slider surface 7. If the position of G is located near theposition where the fluid force is applied, the variation of the contactforce may be reduced. In this case, the projection 13 requires onlymass, so the structure or material are not limited. The structure ofthis embodiment can be applied to each of the embodiments describedabove.

A structure of a magnetic head device according to a ninth embodiment ofthe present invention will be described with reference to FIG. 10.

The purpose of this embodiment is to reduce the variation of the contactforce caused by the positioning error between the slider surface and thecontact portion.

The slider surface 7 is a convex surface, which confronts the disk andis curved along the rotating direction of the disk. The center of itscurvature is near the pivot position 6 where a load F is applied. Thedistribution of the dynamic pressure (gage pressure) Ph is shown in FIG.10. The position 8, where the fluid force fh is applied, is located nearthe portion which is closest to the disk.

When the positioning error between the slider surface 7 and the contactportion 4 is made, the contact force fc varies. This variation of thecontact force fc will be described with reference to FIGS. 11(a)-11(c).FIG. 11(b) shows the standard condition. FIG. 11(a) shows the conditionthat the contact portion 4 is recessed by Δ from the contact portion ofthe standard condition. FIG. 11(c) shows the condition that the contactportion 4 is projected by Δ from the contact portion of the standardcondition.

When the contact portion 4 is recessed by Δ, the posture of the slider 2changes, so that the pitching angle increases (+θ″). The position 8where the fluid force fh is applied is still located near the portionwhich is closest to the disk. The distribution of the dynamic pressurePh does not change. If some conditions that will be described aresatisfied, it is possible to keep the distribution of the dynamicpressure ph to be constant. These conditions relate the length of theslider surface 7 along to the rotating direction of the disk, and theradius of the curvature of the slider surface 7. According to thecombination of the length and the radius of the curvature, the dynamicpressure becomes equal to the atmospheric pressure in the range of theslider surface 7.

According to the change of the the posture of the slider 2, the distancelh between the position 8 and the contact portion 4, and the distance lpbetween the pivot position 6 and the contact portion 4, changes verylittle. The distance lh−lp between the pivot position 6 and the position8 is shown in the following equation (4).

(lh−lp)−(lh″−lp″)=Rp·θ″  (4)

“Rp” is the distance between the center of the curvature (O) of theslider surface and the pivot position 6.

This distance between positions 6 and 8 is shorter than that in thestandard condition. The distance between the position 8 and the contactportion 4 changes very little.

lh″=lh  (5)

As a result, the variation of the contact force (dfc) is shown in thefollowing equation (6). $\begin{matrix}{{dfc} = \frac{{Rp} \cdot \theta^{''}}{1h}} & (6)\end{matrix}$

If the center of the curvature (O) of the slider surface is located nearthe pivot position 6, it is possible to reduce the variation of thecontact force (dfc). If the center of the curvature of the slidersurface (O) coincides with the pivot position 6, the contact force doesnot vary.

With reference to FIG. 11(c), when the contact portion 4 is projected byΔ, the posture of the slider 2 changes, so that the pitching angledecreases (−θ′). According to the change of the the posture of theslider 2, the distance lh between the position 8 and the contact portion4, and the distance lp between the pivot position 6 and the contactportion 4, changes very little. The distance between the pivot position6 and the position 8 is shown in the following equation (7).

(lh′−lp′)−(lh−lp)=Rp·θ′  (7)

The distance between positions 6 and 8 is longer than that in thestandard condition. The distance between the position 8 and the contactportion 4 changes very little.

lh′=lh  (8)

So the variation of the contact force (dfc) is shown in the followingequation (9).

$\begin{matrix}{{dfc} = \frac{{Rp} \cdot \theta^{\prime}}{1h}} & (9)\end{matrix}$

Thus, if the center of the curvature (O) of the slider surface islocated near the pivot position 6, it is possible to reduce thevariation of the contact force (dfc). If the center of the curvature (O)of the slider surface is coincides with the pivot position 6, thecontact force does not vary.

According to this embodiment, if the dimensional accuracy of the pivotposition is assured, it is possible to keep the contact force at a lowlevel without the influence of the accuracy of manufacturing. Thestructure of this embodiment can be applied to each of the embodimentsdescribed above.

A structure of a magnetic disk drive in which use the head of thepresent invention is used, will be described with reference to FIG. 12.

A disk 201 is set on a spindle 202, and rotated at a constant rotationalspeed by the spindle 202. A slider 203 carrying a magnetic pole ismounted on a tip end of a suspension 204, and accesses to the disk 201in order to read and write data. The suspension 204 is connected to anend of an arm 205 which has a bobbin portion holding a driving coil (notshown). The other end of the arm 205 has a voice coil motor 206, whichis a type of linear motor. The arm 205 is held by ball bearings (notshown) provided in two locations, i.e. above and below a fixing axis207, and the arm 205 can be freely rotated and/or oscillated by thevoice coil motor 206. The voice coil motor 206 has a driving coil woundaround the bobbin portion of the arm 205, and a magnetic circuit formedof a permanent magnet (not shown) arranged to sandwich the coil and tooppose each other, and an opposing yoke (not shown).

The head of the present invention is not limited to being applied to amagnetic disk drive in which a rotary actuator is used. It is possibleto apply it to other types of magnetic disk drives, for example, amagnetic disk drive in which a linear actuator is used.

Thus in accordance with the magnetic head device according toembodiments of the present invention, a position where a sum of thedynamic pressure (fluid force) is applied, is located far from thecontact portion, so a distance between the position where the fluidforce is applied and the contact portion becomes long. Consequently, itis possible to keep the contact force low.

Further, a distance between the position of a center of gravity of themagnetic head device and the contact portion becomes long. So it ispossible to reduce the variation of the contact force according toinertia which occurs by the undulation of the medium, the vibration ofthe medium, or the shock applied to the device from outside.

Further in accordance with the magnetic head device according toembodiments of the present invention, the inertia caused by theundulation of the medium, the vibration of the medium, or an externalshock applied to the device is balanced with the fluid force only, sothe contact force does not vary.

Also in accordance with the magnetic head device according toembodiments of the present invention, if the posture of the sliderchanges, it is possible to keep the distribution of the dynamic pressureconstant. Consequently, it is possible to reduce the variation of thecontact force caused by the positioning error between the slider surfaceand the contact portion.

Additionally in accordance with the magnetic disk drive according toembodiments of the present invention, it is possible to keep the contactforce which is applied to the magnetic head device at a low level, andto reduce the variation of the contact force according to inertia causedby the undulation of the disk, the vibration of the disk, or an externalshock applied to the device. Consequently, the life of the magnetic diskdrive can be extended, because wear of the magnetic head device and themagnetic recording disk can be reduced.

Additionally in accordance with the magnetic disk drive accordingembodiments of the present invention, the inertia caused by theundulation of the medium, the vibration of the medium, or an externalshock applied to the device is balance with the fluid force which isapplied to the magnetic head device only, so the contact force does notvary. Consequently, the life of the magnetic disk drive can be extended,because wear of the magnetic head device and the magnetic recording diskcan be reduced.

Further in accordance with the magnetic disk drive according toembodiments of the present invention, if the posture of the magnetichead device changes, it is possible to keep the distribution of thedynamic pressure constant. As a result, it is possible to reduce thevariation of the contact force caused by the positioning error betweenthe slider surface and the contact portion. Consequently, the life ofthe magnetic disk drive can be extended, because wear of the magnetichead device and the magnetic recording disk can be reduced.

Additional advantage and modifications will readily occur to thoseskilled in the art. Therefore, the present invention in its broaderaspects is not limited to the specific details, representative devices,and illustrated examples shown and described herein. Accordingly,various modifications may be made without departing from the spirit orscope of the general inventive concept as defined by the appended claimsand their equivalents.

What is claimed is:
 1. A magnetic head device for reading informationfrom or writing information to a rotating magnetic recording medium,comprising: a magnetic pole for reading the information from or writingthe information to the medium; and a slider for supporting said magneticpole and for moving said magnetic pole on the medium, said sliderincluding a contact portion for maintaining contact between the magneticpole and the medium, the contact portion being joined directly to saidmagnetic pole, a flying portion for flying above the medium when themagnetic pole moves on the medium, the flying portion having a surfacefor facing the medium, the surface having a length in a rotatingdirection of the medium and a width in a direction perpendicular to therotating direction of the medium and along the surface of the flyingportion, the width being greater than the length, a connecting portionbeing coupled between the contact portion and flying portion, theconnecting portion having a surface for facing the medium, the surfaceof the connecting portion being recessed from the surface of the flyingportion, wherein a dynamic pressure generated by fluid-flow caused byrotation of the medium and acting on the slider is applied mainly to thesurface of the flying portion.
 2. A magnetic head device according toclaim 1, wherein the surface of the flying portion includes a firstsurface and a second surface, the first surface being angled withrespect to the second surface in the rotating direction of the medium sothat an end of the first surface is further from the medium than thesecond surface when the medium is stationary, the second surface beingsubstantially parallel to the medium when the medium is stationary.
 3. Amagnetic head device according to claim 1, further comprising a loadapplying first surface for applying a load to said slider, the loadbalancing with a resultant force of the dynamic pressure and a contactforce applied by the medium to the contact portion.
 4. A magnetic headdevice according to claim 3, wherein an end of the contact portion and aposition of a center of gravity of a combination of a mass of the sliderand an equivalent mass of said load applying member are spaced apart bya first distance, and wherein the end of the contact portion and aposition where the resultant force of the dynamic pressure is appliedare spaced apart by a second distance, the first distance beingsubstantially equal to the second distance.
 5. A magnetic head deviceaccording to claim 1, wherein an entire area of the surface of theconnecting portion is less than an entire area of the surface of theflying portion.
 6. A magnetic head device according to claim 1, whereinthe connecting portion has a mass less than that of the flying portion.7. A magnetic head device according to claim 1, wherein the surface ofthe flying portion is concave in a direction perpendicular to therotating direction of the medium.
 8. A magnetic head device according toclaim 1, wherein the surface of the flying portion is convex in adirection perpendicular to the rotating direction of the medium.
 9. Amagnetic disk drive comprising: a magnetic recording disk; a rotatingdevice for rotating the disk; and a magnetic head device including amagnetic pole for reading information from or writing information to thedisk, and a slider for supporting said magnetic pole and for moving saidmagnetic pole on the disk, said slider including a contact portion formaintaining contact between the magnetic pole and the disk, the contactportion being joined directly to said magnetic pole, a flying portionfor flying above the disk when the magnetic pole moves on the disk, theflying portion having a surface for facing the disk, the surface havinga length in a rotating direction of the disk and a width in a directionperpendicular to the rotating direction of the disk and along thesurface of the flying portion, the width being greater than the length,a connecting portion being coupled between the contact portion and theflying portion, the connecting portion having a surface for facing thedisk, the surface of the connecting portion being recessed from thesurface of the flying portion, wherein a dynamic pressure generated byfluid-flow caused by rotation of the disk and acting on the slider isapplied mainly to the surface of the flying portion.
 10. A magnetic diskdrive according to claim 9, wherein the surface of the flying portionincludes a first surface and a second surface, the first surface beingangled with respect to the second surface in the rotating direction ofthe disk so that an end of the first surface is further from the diskthan the second surface when the disk is stationary, the second surfacebeing substantially parallel to the disk when the disk is stationary.11. A magnetic disk drive according to claim 3, further comprising aload applying member for applying a load to said slider, the loadbalancing with a resultant force of the dynamic pressure and a contactforce applied by the disk to the contact portion.
 12. A magnetic diskdrive according to claim 11, wherein an end of the contact portion and aposition of a center of gravity of a combination of a mass of the sliderand an equivalent mass of said load applying member are spaced apart bya first distance, and wherein the end of the contact portion and aposition where the resultant force of the dynamic pressure is appliedare spaced apart by a second distance, the first distance beingsubstantially equal to the second distance.
 13. A magnetic disk driveaccording to claim 9, wherein an entire area of the surface of theconnecting portion is less than an entire area of the surface of theflying portion.
 14. A magnetic disk drive according to claim 9, whereinthe connecting portion has a mass less than that of the flying portion.15. A magnetic disk drive according to claim 9, wherein the surface ofthe flying portion is concave in a direction perpendicular to therotating direction of the disk.
 16. A magnetic disk drive according toclaim 9, wherein the surface of the flying portion is convex in adirection perpendicular to the rotating direction of the disk.
 17. Amagnetic head device for reading information from or writing informationto a rotating magnetic recording medium, comprising: a magnetic pole forreading the information from or writing the information to the medium;and a slider for supporting said magnetic pole and for moving saidmagnetic pole on the medium, said slider including a contact portion formaintaining contact between said magnetic pole and the medium, thecontact portion being joined directly to said magnetic pole, a flyingportion for flying above the medium when the magnetic pole moves on themedium, the flying portion having a surface for facing the medium, thesurface having a length in a rotating direction of the medium, and aconnecting portion being coupled between the contact portion and theflying portion, the connecting portion having a length in the rotatingdirection of the medium, the connecting portion having a surface forfacing the medium, the surface of the connecting portion being recessedfrom the surface of the flying portion, wherein a dynamic pressuregenerated by fluid-flow caused by rotation of the medium and acting onthe slider is mainly applied to the surface of the flying portion, andthe length of the connecting portion's surface in the rotating directionof the medium is greater than the length of the flying portion's surfacein the rotating direction of the medium.
 18. A magnetic head deviceaccording to claim 17, wherein the surface of the flying portion has awidth in a direction perpendicular to the rotating direction of themedium, and the width of the surface of the flying portion is greaterthan the length of the surface of the flying portion.
 19. A magnetichead device according to claim 17, wherein the surface of the flyingportion includes a first surface and a second surface, the first surfacebeing angled with respect to the second surface in the rotatingdirection of the medium so that an end of the first surface is furtherfrom the medium than the second surface when the medium is stationary,the second surface being substantially parallel to the medium when themedium is stationary.
 20. A magnetic head device according to claim 17,further comprising a load applying member for applying a load to saidslider, the load balancing with a resultant force of the dynamicpressure and a contact force applied by the medium to the contactportion.
 21. A magnetic head device according to claim 20, wherein anend of the contact portion and a position of a center of gravity of acombination of a mass of the slider and an equivalent mass of said loadapplying member are spaced apart by a first distance, and wherein theend of the contact portion and a position where the resultant force ofthe dynamic pressure is applied are spaced apart by a second distance,the first distance being substantially equal to the second distance. 22.A magnetic head device according to claim 17, wherein an entire area ofthe surface of the connecting portion is less than an entire area of thesurface of the flying portion.
 23. A magnetic head device according toclaim 17, wherein the connecting portion has a mass less than that ofthe flying portion.
 24. A magnetic head device according to claim 17,wherein the surface of the flying portion is concave in a directionperpendicular to the rotating direction of the medium.
 25. A magnetichead device according to claim 17, wherein the surface of the flyingportion is convex in a direction perpendicular to the rotating directionof the medium.
 26. A magnetic disk drive comprising: a magneticrecording disk; a rotating device for rotating said disk; and a magnetichead device including a magnetic pole for reading the information fromor writing the information to the disk; and a slider for supporting saidmagnetic pole and for moving said magnetic pole on the disk, said sliderincluding a contact portion for maintaining contact between saidmagnetic pole and the disk, the contact portion being joined directly tosaid magnetic pole, a flying portion for flying above the disk when themagnetic pole moves on the disk, the flying portion having a surface forfacing the disk, the surface having a length in a rotating direction ofthe disk, and a connecting portion being coupled between the contactportion and the flying portion, the connecting portion having a lengthin the rotating direction of the disk, the connecting portion having asurface for facing the disk, the surface of the connecting portion beingrecessed from the surface of the flying portion, wherein a dynamicpressure generated by fluid-flow caused by rotation of the disk andacting on the slider is mainly applied to the surface of the flyingportion, and the length of the connecting portion's surface in therotating direction of the disk is greater than the length of the flyingportion's surface in the rotating direction of the disk.
 27. A magneticdisk drive according to claim 26, wherein the surface of the flyingportion has a width in a direction perpendicular to the rotatingdirection of the medium, and the width of the surface is greater thanthe length of the surface.
 28. A magnetic disk drive according to claim12, wherein the surface of the flying portion includes a first surfaceand a second surface, the first surface being angled with respect to thesecond surface in the rotating direction of the disk so that an end ofthe first surface is further from the disk than the second surface whenthe disk is stationary, the second surface being substantially parallelto the disk when the disk is stationary.
 29. A magnetic disk driveaccording to claim 26, further comprising a load applying member forapplying a load to said slider, the load balancing with a resultantforce of the dynamic pressure and a contact force applied by the disk tothe contact portion.
 30. A magnetic disk drive according to claim 29,wherein an end of the contact portion and a position of a center ofgravity of a combination of a mass of the slider and an equivalent massof said load applying member are spaced apart by a first distance, andwherein the end of the contact portion and a position where theresultant force of the dynamic pressure is applied are spaced apart by asecond distance, the first distance being substantially equal to thesecond distance.
 31. A magnetic disk drive according to claim 26,wherein an entire area of the surface of the connecting portion is lessthan an entire area of the surface of the flying portion.
 32. A magneticdisk drive according to claim 26, wherein the connecting portion has amass less than that of the flying portion.
 33. A magnetic disk driveaccording to claim 26, wherein the surface of the flying portion isconcave in a direction perpendicular to the rotating direction of thedisk.
 34. A magnetic disk drive according to claim 26, wherein thesurface of the flying portion is convex in a direction perpendicular tothe rotating direction of the disk.